Variable predetermined number pulse generator



March 1, 1949. R. w. CARLSON VARIABLE PREDETERMINED NUMBER PULSE GENERATOR 2 Sheets-Sheet 1 Filed Aug. 14, 1944 Patented Mar. 1, 1949 VARIABLE PREDETERMINED NUMBER PULSE GENERATOR Robert W. Carlson, Depew, N. Y., assignor to Colonial Radio Corporation, Buffalo, N. Y.

Application August 14, 1944, Serial No. 549,317 I 4 Claims. 1

' pulse groups consisting of 2, 3, 4, 5, and '7 pulses respectively, these pulses being of the order-of a few microseconds duration, and the spacing between successive pulses being always 1 millisecond. It will be understood, however, that in accordance with the principles of my invention, the duration'of the pulses may be different and the time interval between successive pulses may also be different.

When used with receivers which respond selectively to the number of incoming pulses, a .very effective remote control system may be provided for operating various mechanisms.

It is an object of this invention to provide apparatus of the class described, by means of which any one of a number of predetermined pulse combinations may be produced, the varying pulse combinations being made up of a different number of pulses of the same length always occurring at the same rate or with the same time interval between successive pulses.

It is a further object of this invention to provide apparatus of the class described capable of delivering pulses of a few microseconds duration with a spacing between, successive pulses of the order of 1 millisecond.

It is still a further object of this invention to provide apparatus of the class described, in which interval between the pulses may be readily adjusted or controlled.

It is still a further object of this invention to provide apparatus of the class described which shall be positive, reliable,.and unfailing in operation.

Still other objects and advantages of my invention will be apparent from the specification.

. The features of novelty which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its fundamental principles and as to its particular embodiments,

will best be understood by reference to the specification and drawing, in which Fig. 1 is a circuit diagram of one form of cirthe time duration of the pulses and the time cuit according to my invention and Figs. 2a to 2e, 3a to Sc, 4a to 4e, 5a to 5e, 6a to Be, and

7a to 7e are curves illustrating the operation of .pulse keyer according to the embodiment of my invention disclosed herein is arranged so as to be capable of producing five difierent and distinctive signals, and for this purpose switches SI, S2, S3, and S4 are provided, connected so that any one of four different distinctive signals may be produced by closure of any one of the switches SI to S4.

Each oneof the switches is provided with a front contact, normally open, against which the blade of the switch may be closed, and each is provided with a back contact which is normally closed (biased to back contact) but is opened when the switch is moved to close on front contact.

Back contact SI!) of switch SI is connected to the blade of switch S2, back contact 82b of switch S2 is connected to the blade of switch S3, and back contact S3?) of switch S3 is connected to blade of switch S4, so that it will be seen that when no switch is closed a circuit is completed through the back contacts of all the switches in series. This corresponds to the fifth condition, and when this condition exists, a clearing signal is sent.

It will be seen further that upon closure of any one of switches SI to S4 against its front contact SI), S21, S3 or SM, the series circuit through all of the switches will be interrupted and the control circuit will be established through the switch which is closed. Conversely, when this switch is released, it closes on its back contact and re-es'tablishes the clearing control circuit.

Control is established through resistances RI, R2, R3, and R4 connected in series from the +3 source to ground when the respective switch is closed. The common point of resistances RI and R2 may be connected to front contact S4! of switch St, the common point of resistances 2 and 3 to front contact S3 of switch S3, the common point of resistances 3 and 4 to front contact S2 of switch S2, and the other point of resistance 4 to front contact SI 1 of switch SI. The blades of switches SI to s4 inclusive may be connected to ground when in back contact position.

The common point of resistances R3 and R4 may be connected to ground through condenser C4, the common point of resistances R2 and R3 to ground through condenser C5, and the com:- mon point of resistances RI and R2 to ground through condenser C6; and a condenser C3 may be connected from ground to front contact SIf of switch SI.

Condenser CI and resistance R5 may be connected in series across condenser C3,.and the voltagedeveloped across resistance R5 may be impressed on the input circuit of tube TI. This tube may be a tube of the thyratron type having cathode Tlc, control electrode Tlg, shield grid TIsa, and anode Tla; a

The common point of resistance R5 andcondenser CI may be connected to the control electrode TI g of tube TI, and the common point of resistance R5 and condenser C3 to cathode TIc'. Anode TIa may be connected through resistance R8 to the source of B voltage, and screen grid TIsg may be connected through resistance R3 to cathode Tlc and through condenser C2 and resistance R1 to the +3 supply.

The common point of condenser C2 and resistance R'I may be connected to ground through condenser 01 and also to back contact S4!) of switch S4. Blade of switch SI may be connected to ground. The output of anode .TIa may be impressed upon tube T2 through condenser C8 and resistance RI2.

Tube T2 may comprise cathode T20, control grid T29, and anode,T2a. Cathode T2c may be connected to ground through resistance RI3 and control electrode T2g to ground through resistance RI2. Anode T2a. may be connected directly to the +3 source.

A blocking oscillator is provided, comprising tube-T3, which may have cathode T30, control electrode T3g, and anode T3a. The cathode may a be connected to ground'and the anode through the primary IIlp of feedback transformer III, and through condenser CI I to cathode T of tube T2.

The common point ofwinding I09 and condenser CII may be connected to ground through resistance RI4. The secondary Ills of feedback transformer I0 may be connected at one end to ground and at the other through resistance RIIl and condenser C9 in parallel to control electrode in Fig. 2a, wherein the dotted line represents zero or ground voltage.

The thyratron TI has previously been ionized, and the constants of the circuit are so chosen that the plate current is limited to about 0.3 ma. The value of resistance R8 may be of the order of 0.5 megohm. Resistance R9, which may be from 0.5 to 1 megohm, forms a bleeder network which may be connected to ground through resistance RI5 shunted by condenser CH) and to'the +B supply through resistance RIG.

The operation of the circuit will now be described. Suppose that switch I is closed on its front contact S I f. This opens the clearing circuit which previously existed in series through the back contacts of switches SI to S4, and grounds the common point of resistance R4 and condenser C3. Since condenser CI has previously, been charged to the value of the +3 supply through the connection afforded by resistances RI, R2, R3, and R4, closure of switch SI applies a strong negative pulse to the control grid of thyratron TI. This pulse leaks to ground in a time interval determined by the constants of the circuit formed by resistance R5 and condensers CI, as shown keeps the plate voltage within arvalue such that the weakest negative pulse applied to the control electrode Tlg of tube TI is sumcient to deionize thetube.

When the negative pulse is applied to control electrode 'TIg by closure of switch SI on front contact, tube TI will deionize for the period of time represented in Fig. 2a by the intersection of the pulse curve with the zero axis. When thyratron TI deionizes at the beginning of the negative pulse, its plate voltage rises and remains at its full positive value until the negative impulse on the grid has been dissipated, at which time the tube reionizes and the plate voltage drops due to the increased I. R. drop in resistance R9. The plate voltage, therefore, has a pulse form as shown in Fig. 3a, the length of which is equal to the time tube TI was deionized, and this depends on the time constant of the resistance R5 and capacity CI associated with switch SI.

While switch SI has been closed, the clearing circuit through the back contacts has been open, and thus condenser C2 is permitted to charge through resistor R1. When switch SI is released, it goes to back contact and the circuit is ready to start another operation. In this connection it may be pointed out that the thyratron TI is preferably a type which will ionize in less than a microsecond.

Should any of the other switches S2, S3, or $4 have been closed instead of switch SI, the action would have been the same except that the resistances and capacities associated with these switches are so chosen as to give a longer pulse. This is shown in Figs. 2b, 2c, and 2d, corresponding to closure of switches S2, S3, and S4, each producing a pulse of longer duration than the previous one.

Closure of any one of the switches SI to S4 against its back contact at the conclusion of its closure on front contact causes discharge of condenser C2 and applies a strong negative pulse on the shield grid TIsg', and this causes deionization of tube TI in the same manner as if the pulse had been applied to control electrode Tlg. The time constant of the circuit associated with condenser C2 is such that tube TI remains deionized for a longer period than for closure of switches SI, S2, S3, or S4 on front contact.

, The pulse in the plate voltage is thus of progressively increasing length for closure of switches SI, S2, S3, and S4, and for the clearing pulse, as shown in Figs. 3a, 3b, 3c, 3d, and 3e. These pulses are applied to control electrode T2g of tube T2 through coupling condenser C8 and are amplified by tube T2. The output of tube T2 is taken from its cathode T20 and applied to the plate of blocking oscillator T3. This connection provides a pulse which is still positive, but in a circuit of lower impedance than that of the plate of tube TI.

Transformer I0 associated with tube T3 and the constants of condenser C9 and resistance RI 0 are such that the blocking and unblocking cycle is controlled by the RC. circuit, and this may be made to have a blocking frequency of 1,000 cycles per second. The plate voltage of tube T3 is indifor switch S2, three blocking cycles; for switch S3, four blocking cycles; for switch S4, five blocking cycles; and for closure of any of the foregoing back to its original (and normal) position, seven blocking cycles. The output of this oscillator is inherently pulse shaped, as shown in Figs. a, 5b, 5c, 5d, and 5e, and these pulses may then be applied to control electrode T4 of thyratron T4.

This tube is biased so that it is normally deionized and will ionize with the application of the pulses from the blocking oscillator. In the plate circuit of thyratron T l there may be provided an artificial line AL, which is discharged when the tube is ionized. The discharge time of the line may be in the order of microseconds, and its charging time less than the time between successive pulses of the blocking oscillator, so that the line is always ready to discharge. Since the design and construction of artificial lines is well known in the art and forms per se no part of this invention, the same is not described in detail.

Negative pulses are available across the load resistor RI I and have the form indicated in Figs.

7a to 7e, corresponding to closures of switches Si on back contact respectively. Should positive pulses as indicated in Figs. 6a to Sc be desired, resistor i5 may be split and one leg isolated from ground by condenser CH] and the positive pulses taken from the high side of the isolated resistor which matches the artificial line AL.

Thus, with the blocking oscillator operatin at 1,000 cycle blocking rate, the final pulse output is pulses of microseconds length, depending upon the constants of the artificial line, and with the repetition rate depending upon the blocking frequency of the blocking oscillator.

While I have shown and described certain preferred embodiments of my invention, it will be understood that modifications and changes may be made without departing from the spirit and scope thereon, as will be clear to those skilled in the art.

In this application I have explained the principles of my invention and the best mode in which I have contemplated applying those principles, so as to distinguish my invention from other inventions; and I have particularly pointed out and distinctly claimed the part, improvement, or combination which I claim as my invention or discovery.

I claim:

1. In a pulse modulator circuit, in combination. a blocking oscillator having its constants so chosen as to generate pulses at a periodic rate, means for applying triggering voltages of different time length to said oscillator to provide groups of pulses of different numbers of pulses, an artificial line, means for maintaining said line always in a condition ready for discharge a thyratron having its plate connected to said artificial line to provide a discharge circuit therefor at a rate determined by said blocking oscillator, and for a time duration determined by said artificial line and means for controlling ionization of said thyraton in accordance with the pulses delivered by said blocking oscillator.

2. In a pulse modulator circuit, in combination,

a thyratron having a pair of control electrodes, a cathode and an anode, a pluralitrof switches,

each-having front and back contact and being,

normally biased to back contact, said switches being interconnected to provide an operating signal when all switches are closed on back contact and being selectively closable on front contact to provide a different operating signal, a time delay circuit for each operating signal, said time delay circuits corresponding to operating signals for front contact closures being connected to one of said control electrodes and said cathode whenever the corresponding switch is closed on front contact, and the time delay circuit corresponding to the back contact closure being connected to said cathode and the other of said control electrodes when all of said switches are closed on back contact.

3. In a pulse modulator circuit, in combination, a thyratron having a cathode, an anode, anda plurality of control electrodes, said thyratron having its constants so chosen as to be normally ionized, a plurality of time delay circuits connected between said cathode and one of said control electrodes for impressing on said control electrode negative pulses of varying duration to cause deionization of said thyratron forthe duration of said pulses, and an additional time delay circuit connected to said cathode and to the other of said control electrodes, said last mentioned circuit being inoperative when any other time delay circuit is connected to said thy atron.

4. In a pulse modulator circmt, in combination, a plurality of control switches, each switch having front and back contacts and being biased to back contact, said switches being interconnected so that when all are closed on back contact an operating circuit is established, an ionized thyratron, means for applying, to said ionized thyratron, deionizing impulses of different length characteristic of closure of each particular switch and of closure of all on back contact, to deionize said thyratron for different times corresponding to each impulse; means for deriving a pulse form potential difference from the output circuit of said thyratron, means for producing groups of periodic discharges of pulse form, and means for controlling the length of said groups of said periodic discharges of pulse form in accordance with the pulse form potential difference derived from the output of said thyratron, to control the number of periodic pulses in accordance with closure of each particular switch.

ROBERT w. CARLSON.

REFERENCES CITED The following references. are of record in the file of this patent:

UNITED STATES PATENTS Great Britain Feb. 1, 1943 

